1. Field of the Invention
In general, the present invention relates to jacks and similar elevation devices that are used to elevate a section of a vehicle for the purpose of changing a tire.
2. Prior Art Statement
There exist many situations where it is desirable to elevate a portion of an automobile. Many of those situations are encountered by mechanics whose job it is to repair and maintain vehicles. However, the situation that is most encountered by the average vehicle driver, is when the vehicle has a flat tire and the tire must be changed.
Most all vehicles come equipped with some form of mechanical jack and a spare or temporary tire. If a vehicle has a flat tire, this equipment enables a person to elevate the vehicle near the flat tire, and replace the flat tire. In the prior art record, a large variety of mechanical jacks have been developed. Most modern vehicles come equipped with either a piston jack device, a scissor jack device or a ratchet jack device. A piston jack device is a mechanical/hydraulic jack device that includes a collapsible hydraulic piston that is placed under a vehicle. A rod is then used to turn a screw at the base of the piston. The turning of the screw is used to create hydraulic pressure in the piston that causes the piston to expand and lift the vehicle. The disadvantages of piston jacks are that they have a limited lifting height, they are difficult to place under the frame of a vehicle and they are hard to operate when in place under a vehicle.
Scissor jack devices are mechanical jacks, where a screw is used to close a set of linkages arranged in a scissor configuration. As the screw is turned, the linkages close and the length of the scissor jack expands. The disadvantages of scissor jacks are that they tip easily, they are difficult to place under the frame of a vehicle and they also are hard to operate when in place under a vehicle.
Ratchet jack devices are mechanical jacks where a lifting hook is advanced on a vertical shaft with a ratchet mechanism. Ratchet jacks are easier to operate than are piston jacks and scissor jacks. However, ratchet jacks cannot be placed under a vehicle. Rather, they must be attached to an exterior portion of the vehicle, such as a bumper. As such, ratchet jacks cannot be used on many modern automobiles that have plastic bumpers that are incapable of supporting the weight of the vehicle.
Since ratchet jacks cannot be used with many modern automobiles, these automobiles typically come equipped with either a piston jack or a scissor jack. As has been previously mentioned, both of these types of jacks are difficult to set into place and operate. In both cases, the jack must be placed between the ground and the vehicle at some point under the vehicle. This often requires a person to lie on the ground to properly position the jack. Once positioned, a person must typically kneel or sit on the ground to operate the jack. Accordingly, the task of simply using a vehicle jack is a task that is beyond the ability of many people and is highly inconvenient for most others.
In an attempt to improve the ease of using a jack, many jacking devices have been invented that do not require a person to manually operate the jack. For instance, in the prior art record, there are many hydraulic jack devices that are manufactured as part of a vehicle. These jacks are always in place and can be operated with the switch of a lever within the automobile. However, such jack devices are extremely expensive and cannot be added to existing vehicles in a cost effective manner.
The prior art record also contains electric jacks that are placed under vehicles and are operated using power from the cigarette lighter of the vehicle. Such electric jacks are also very expensive as compared to manually operated jacks.
Other types of jacks that exist in the prior art are jacks that convert forward movement of an automobile into an elevating force. With this kind of jack, a tiltable framework is placed under the vehicle. The vehicle is then moved forward. As the vehicle moves forward, the framework tilts and a portion of the vehicle is elevated by the framework. Such prior art jack devices tend to be large, expensive and only work in limited situations. As such, they are typically owned by automobile repair shops and are not carried in a vehicle to change a flat tire.
A need therefore exists for a new type of low cost jack device that has a greatly simplified method of installation and operation. In this manner, people previously incapable of jacking up their vehicle can do so in a manner that is convenient, simple and not highly physically intensive. This need is met by the present invention jack assembly as described and claimed below.
The present invention is a jack device and its associated method of elevating a vehicle. The jack device includes an elongated shaft having a first end and a second end. At least one front wheel is supported by the first end of the shaft. A platform is connected to the opposite second end of the shaft. It is the platform that contacts and lifts the underside of a vehicle. To elevate the platform at the second end of the shaft, a frame structure is connected to the shaft with a hinged connection. The frame structure supports at least one rear wheel.
A spool is connected to at least one of the wheels supporting the jack device. A flexible element extends from the spool. The flexible element extends across the hinged connection between the shaft and the frame structure. As the jack assembly is moved forward, the wheels turn and the spool turns. As the spool turns, the flexible element winds around the spool and becomes taut. This pulls the frame structure toward the shaft, thereby elevating the lifting shaft and the platform at the end of the shaft.
To utilize the jack device, the jack device is placed under a vehicle. The platform of the jack device is then engaged with the frame of the vehicle. The vehicle is then moved forward. As the vehicle moves forward, the jack device rolls forward. This causes the jack device to elevate the platform and lift the vehicle. To lower the vehicle, the vehicle is placed in a neutral gear and is pushed backwards. This causes the jack device to roll in reverse, thereby lowering the platform.